Re: COPY/FTP error

Hi There Ian,

I should have mentioned that the servers are in two locations - about 10 miles apart. The network is pretty good by all accounts and even with the major traffic from me yesterday (about 8million blocks) worth of files , there was no impact to users of other systems (who also use this link)

Re: COPY/FTP error

Hi,

you've typed CTRL-T a couple of times, but the IO counter only increased by 1 each time, so there were no IOs being done by COPY/FTP. And the copy finally failed, so there has been a network connectivity issue.

If there are packets getting lost on that link between the 2 systems, DECnet will take a lot time to retransmit packets, which will make the perceived 'performance' look bad.

Re: COPY/FTP error

gunners,

This sounds like a duplex mismatch to me. Check that the entire path between systems either has matching settings between NIC and switch ports. I recommend AUTONEGOTIATE everywhere, but if that's not possible, ensure that if any port has a hard setting, that it matches exactly at both ends.

If one end is st to (say) 100 Full Duplex and the other end is AUTO, the auto end will configure as 100 Half Duplex. On a lightly loaded network this is rarely an issue. So things like telnet "work fine". However, when you start loading it with things like file transfers the half duplex end will start missing packets and requesting retransmissions, leading to excessive transfer times and/or timeouts.

Many years ago a myth developed that OpenVMS doesn't handle network autonegotiation. It may have been true of mixtures of specific nics, brands of switches and (ancient) versions of network software, but for anything produced in the last decade or two, everything just works. If your site policies have a voodoo belief in "autonegotiate bad", please try to change it. (On the other hand, the continued prevalence of duplex mismatches keep many support staff in work, with the ability to easily achieve apparently miraculous fixes)

Re: COPY/FTP error

Does PING or TELNET work between those 2 systems ?

You can look at the console messages issued by the LAN driver with $ MC LANCP SHOW DEVICE/INTERNAL

This will show you 'possible duplex mismatch' errors detected and reported by the LAN driver. It will also show you the LAN startup messages, which should tell you the settings of the LAN device(s) at console level, and the link state.

Then you need to talk to your network people about the status of the switch ports, to which the LAN interfaces are connected.

Re: COPY/FTP error

So the sending and receiving servers do not seem to have a problem with autonegotiation settings, both are set to AUTO. And I assume, that there were no 'possible duplex mismatch' messages from the LAN drivers as shown at the bottom of the LANCP SHOW DEV/INT output.

But how about JUMBO frames ? Are the system using JUMBO frames ? If so, are all the network components in the path between those system able to forward jumbo frames ?

What happens, if you try to copy a very small file (1 block) with COPY/FTP ?

Re: COPY/FTP error

ok , no mismatches , i did the lan command to an output file on both and searched both.

I tried a copy/ft of a small file as you suggested and it hangs and times out with 'I/O error on network device' , Device Timeout.

I tried a copy without /ftp and it copied across fine.

Hmmm , Is it possible it could be a problem on the actual network switch , might need to get them to check the settings - is there such a thing as 'autonegoutiate' on the port AS WELL AS the server card (which we have verified is ok)

Re: COPY/FTP error

The switch ports must also be set to auto-negotiate and their current settings should be the SAME as the current settings of the LAN interfaces in your OpenVMS servers.

But if TELNET and DECnet-copy work and FTP copy fails (did you try COPY/FTP x.x localhost::... on the receiving and sending server to make sure the FTP servers are o.k. ?), I guess this might be some problem with a firewall in the path between those servers or a problem with TCP buffer sizes (i.e. the end-to-end buffer size negotiation comes up with a larger buffer size than the intermediate system can handle).

You could run $ TCPTRACE remote-node-IP and/or tcpdump and check the IP packets sent from the local to the remote server.

if the networking folks tell you that the switch port or cable is "OK", definitely verify it.

try a different switch port.

try a different cable.

try a different NIC in the box.

always verify the settings on both ends of the connection match.

ftp tends to show errors more than other protocols as it's a glaringly stupid protocol, wildly insecure, and incompatible with inexpensive firewalls. It's also ancient. Given the option, sftp (with or without certificates) is a far better choice.

And in general, using ftp to transfer BACKUP savesets around is asking for trouble. It's one of the most common causes for corrupt metadata. It's better to use zip "-V" (and yes, you need the -V, and yes, you need to quote the -V switch as "-V") to transfer files around, as that preserves the RMS metadata, and most tools can correctly default a zip archive file extension.